Average distance between points

average_distance.py

from math import pow, sqrt

def distance_two_points(x1, y1, x2, y2):
    return sqrt(pow(x2 - x1, 2) + pow(y2 - y1, 2))

points = [(1, 2), (3, 4), (5, 6)]
sum = 0

for outer_i in range(len(points)):
    for inner_i  in range(len(points)):
        if inner_i != outer_i:
            sum += distance_two_points(*points[outer_i], *points[inner_i])

average_distance = sum/len(points)
print(average_distance)